#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
//int fun(char *s) 
//{ 
//	char *p = s; 
//	while(*p != '\0')
//	{ p++; }
//	return(p-s);
//}
//int main()
//{ 
//	printf("%d\n",fun("goodbye!")); 
//}
char number(char* a, int sz)
{
	int arr[500] = { 0 },len = 0,i;
	for (i = 0; i < sz; i++)
	{int len = a[i];arr[len]++;}
	while (*a!='\0')
	{if (arr[*a] > 1){return *a;}(*a)++;}return 0;}
int main()
{
	char a[] = "qywyer23tdd";
	int sz = sizeof(a) / sizeof(a[0]);
	char w = number(a, sz);
	printf("%c",w);
	return 0;
}